The present invention relates to an earthquake control operating system for an elevator during earthquakes, especially, long-period earthquakes.
A long-period earthquake refers to an earthquake that can hardly be felt by humans. The shaking associated with a long-term earthquake are slow, with a period of several seconds to ten seconds. The longer the period, the more an earthquake is damped such that it can be transmitted several hundred kilometers. A long-period earthquake predominately takes place during major earthquakes. The long-term earthquake is maintained in the soft earth layers and it is amplified in flat regions, thereby enabling it to last for a long time. As a result, tall buildings are apt to resonate with the long-period vibration. The resonance causes building vibrations to increase, thereby possibly causing damage. For example, in the Tokachigawa Earthquake in 2003, a vibration of liquid surfaces in oil tanks occurred, thereby causing two fires.
As described in Japanese Patent Application Nos. 2004-224469 and 2004-284758, an earthquake control operating system for an elevator has been proposed that stops or controls the operation of the elevator before the arrival of the earthquake in the region concerned. However, in the earthquake control operating system for an elevator in the prior art, including the systems described in Japanese Patent Application Nos. 2004-224469 and 2004-284758, there is the following problem: in many cases, it is impossible to detect the vibration of a long-period earthquake. In this case, lateral vibration of a building (building sway) takes place due to the long-period earthquake. As the vibration frequency may be in agreement with the intrinsic vibration frequency of the ropes of elevators (resonance), the elevator equipment may become damaged. In addition, as it may be impossible to detect the long-period earthquake, accidental enclosure of passengers in elevator cars may occur.
Even when a long-period earthquake is detected with an earthquake detector or the like and earthquake control operation is performed, when the vibration becomes lower than the detection level of the earthquake detector, the elevator may automatically (and prematurely) resume operation. As a result, in the case of an enduring long-period seismic wave, secondary hazards may occur.
In addition, even when an earthquake control operation is performed after detection of a long-period earthquake, the earthquake control operation necessarily is executed some time after the detection. The delay between detection and control may be such that the control occurs after earthquake has arrived, i.e., the control may fail to be timely actuated.
In light of the foregoing, the present invention aims to resolve one or more of the aforementioned issues that afflict conventional earthquake control operating systems. More specifically, the present invention aims to solve the aforementioned problems of the prior art by providing an earthquake control operating system for an elevator and an earthquake control operating method for an elevator in which it is possible to ensure passenger safety and to prevent damage to the elevator equipment.